With the development of society, the amount of data is increasing. This requires that optical communication modules transmit data at a faster speed and cost less. Existing 3G technology is unable to meet the complex needs of users and markets. TD-LTE (Time Division-Long Term Evolution, long-term evolution of TD-SCDMA) has emerged as a technology that paves the way from 3G to 4G. Due to the current shortage of optical fiber resources, high cost of new installations, and relatively long distances between base stations, the demand for small form-factor pluggable (SFP+) packaged optical modules has been gradually increasing.
Generally, in an optical module, electrical signals enter a PCBA (Printed Circuit Board Assembly) from gold contact fingers and are then outputted to an optoelectronic chip, which converts the electrical signals into optical signals and output them to an optical port through an optical system. The optical port and the electrical interface (gold contact fingers) are both fixed relative to a housing of the optical module. In general, the PCBA is rigid, the optical system is rigid, and all devices have certain dimensional tolerances.
Most optical module packaging technologies now use a flexible circuit board (FPC) to absorb assembly tolerances. But the solder joints between the flexible circuit board and the PCBA introduce relatively large electrical signal attenuation. Therefore, such optical module packaging technologies can only be used for transmission rates below 10G.
With higher transmission rates, the design of optical modules for long-distance transmission requires smaller attenuation of high-speed electrical signals. At the same time, to meet the assembly requirements of the optical module, it is necessary to assemble the gold contact fingers, PCBA, optoelectronic chip, free-space optical path assembly, and optical port. Thus, a problem that needs to be resolved is how to integrate the design for best conversion between and transmission of optical and electrical signals.